The results show occurrence of the tropopause "weakening" several times during January 3-8, November 9-16 and December 5-10, 1994. Simultaneous observations of ozone profiles particularly on January 7/8, November 10, 16 and December 7/8, 1994, the days of tropopause "weakening," show the evidence of decrease in stratospheric ozone and corresponding increase in tropospheric ozone after this event, the total ozone remaining essentially constant on those days with respect to other days. But tropopause "weakening" on January 4/5, 1994 does not show any considerable change in the ozone profiles. The results are presented here relating the degree of tropopause "weakening" to the extent of vertical mass exchange between troposphere and stratosphere.
An effort has been made to examine the role of horizontal advection of ozone in increasing tropospheric ozone at the region of interest, the geographical distribution of tropospheric ozone residual (TOR) has been analyzed by the two data sets obtained independently from Meteor-3 Total Ozone Mapping Spectrometers (Meteor-3 TOMS) and Upper Air Research Satellite (UARS). Simultaneously the possibility of horizontal transport of ozone from the surroundings of Tirupati and Trivandrum in increasing tropospheric ozone due to synoptic scale circulation has also been verified by close inspection of synoptic weather charts at 1000, 700, 500 and 300 hPa obtained from NCMRWF GCM model at 00 UTC and 12 UTC of January 7 and 00 UTC and 12 UTC of January 8, 1994.